This invention relates generally to a mechanism for adjusting a vehicle headlamp.
Eckenrode U.S. Pat. No. 5,023,759 discloses a headlamp adjusting mechanism for a modern headlamp assembly of the type in which both the high and low beam bulbs are contained in a common housing adapted to be adjusted angularly from inside the vehicle engine compartment in order to properly aim the beam of the headlamp. In the Eckenrode adjuster, an internally threaded worm gear encircles a non-rotatable screw and is operable when rotated to move the screw axially and effect adjustment of the headlamp. Rotation of the worm gear is produced in response to manual rotation of a driver in the form of a worm which extends generally perpendicular to the screw. A plastic housing supports the worm and the worm gear for rotation and constrains the screw against rotation while permitting the screw to move axially back and forth.
The Eckenrode adjuster requires three drive components, namely, the worm, the internally threaded worm gear and the screw. The worm gear requires both internal and external drive components and causes the lateral width of the drive to be relatively large. Moreover, there is a possibility of backlash between the worm and the worm gear on one hand and between the worm gear and the screw on the other hand and thus detrimental fore and aft play of the screw can develop and result in vibration of the headlamp.